The Electro-Voice Q66 II power amplifier is a versatile workhorse with 2 x 600W @ 4 ohms and 2 x 900W @ 2 ohms. It has plenty of power to drive a huge variety of speaker systems, including Sx300, ZX4, Sb122, and more.

Dynamic Headroom:
Electro-Voice's philosophy is that tonal performance of live music counts most; therefore, Electro-Voice amps are designed for dynamic headroom, meaning that each and every Electro-Voice amp—including the Q66 II—has at least 30% more output capability for short-term signals when compared to a long-term sine wave value. This additional headroom results in an amp that will, for example, allow for short term signal peaks of at least 780W when spec'd 600W. While dynamic headroom is audible when playing music through a sound system, another specification to observe is the increase in output power from an 8-ohm load to 4 ohms, and then down to 2 ohms. Of course, all Electro-Voice power amplifiers are designed to be absolutely stable into loads of 2 ohms.

Innovative Class-H power
With Q Series' efficient Class-H design, the permanent voltage rail is designed to cover the average music signal, rather than permanently supplying the voltage for maximum output power. If dynamic peaks require a higher output voltage, the voltage rail is switched to the maximum. This process saves up to 50% of the power consumption found in conventional amplifier design, and results in a dramatic reduction in heat output. The EV Q66 II and other power amps from the Q Series combine the sonic excellence and ruggedness of its Precision Series predecessors with Class-H innovation, all in a compact and affordable package.

Transient Response:
When processing dynamic signals, other important criteria are signal speed and dynamic distortion. For example, kick drum signals carry pulses of many frequencies as an overlay spectrum. Therefore, and in contrast to many other manufacturers, Electro-Voice specifies a lot more information on their amplifiers' dynamic behavior than just "slew rate" figures. Important tests referring to the amp's ability regarding multitone signal pulses are expressed by IMD-SMPTE measurements at high power levels. And, while IMD tests show the Intermodulation Distortion behavior (how much "sound" is added by the amplifier), DIM30 is the real spec for speed in an amplifier. All these tests are carried out in EV labs during an amplifier's design phase, to ensure maximum sonic performance. While these technical explanations appear very complex, they are clearly audible. Take a the Q44 II power amplifier and crank it up—you'll hear the difference immediately.

Protection Package and Dynamic Limiter
Q Series amplifiers benefit from decades of professional amplifier design, and all the expertise that has made EV amps the concert/touring standard is built into Q Series. This complete protection package includes sophisticated circuits against overheating, short circuit, DC output voltage, HF oscillation, back EMF (Electromotive Force), and destructive peak current. Furthermore, Q Series amps also protect your valuable loudspeakers with built-in dynamic limiters, preventing dangerous output clipping. The limiters immediately reduce amp gain when dynamic headroom is pushed to the limits at maximum output, keeping distortion below 1% in a situation that can otherwise cause a signal to clip, which is often fatal for woofers and drivers.